Slurry reactor microreactors

The microreactor technique described by the authors offered 30 and 50 times higher STY values than the conventional tubular reactor and the slurry reactor, respectively, suggesting microreactors to be a successful technique in mass transfer controlled reactions. 

Slurry reactors are often used for intrinsic kinetic measurements. In order to alleviate the effects and complications of the initial heat-up period, as well as the induction period, on the kinetic measurements, novel designs have been introduced. Cup-and-cap reactors, falling-basket reactors, rapid-injection reactors, reactors with induction heaters, and microreactors are five such novel designs. Each of these reactors has been found to be successful the first three, however, consider both induction and heat-up periods. The last two reactors alleviate the complications due to the heat-up period only. All of these... 

Gas-solid batch microreactor, initial outgassing of the catalyst for 2 h at 5(X) °C under vacuum (2) gas-liquid-solid slurry reactor, n-heptane liquid phase, 6 °C, 100 % conversion of ethylene, run time 34 h... 

The reaction progress is monitored ofF-Une by HPLC. Flow rates, residence times and initial concentrations of 4-chlorophenol are varied and kinetic parameters are calculated from the data obtained. It can be shown that the photocatalytic reaction is governed by Langmuir-Hinshelwood kinetics. The calculation of Damkohler numbers shows that no mass transfer limitation exists in the microreactor, hence the calculated kinetic data really represent the intrinsic kinetics of the reaction. Photonic efficiencies in the microreactor are still somewhat lower than in batch-type slurry reactors. This finding is indicative of the need to improve the catalytic activity of the deposited photocatalyst in comparison with commercially available catalysts such as Degussa P25 and Sachtleben Hombikat UV 100. The illuminated specific surface area in the microchannel reactor surpasses that of conventional photocatalytic reactors by a factor of 4-400 depending on the particular conventional reactor type. 

A cartridge heater is inserted in the cover plate of the packed-bed reactor [277]. The base plate provides conduits to the microreactor. The outlets are standard high-pressure fittings. Thermocouples are inserted into the slurry feed channels. 

When the catalyst is available in a small amount, a microreactor assembly is often used (Miller, 1987). This is a simple T-type reactor heated by a fluidized sand bath. The mixing is provided by mechanical agitation that shakes the reactor up and down within the fluidized bed. Because of the small amount of slurry, and an effective heat transfer in the fluidized sand bath, the heat-up period in such a reactor is small. The nature of mechanical agitation is, however, energy-efficient. The reactor provides only a small sample for the product analysis, which makes the usefulness of the reactor for detailed kinetic measurements somewhat limited. The reactor has been extensively used for laboratory catalyst screening tests in coal liquefaction. 

Multiphase packed-bed or trickle-bed microreactor [29, 30] Standard porous catalysts are incorporated in silicon-glass microfabricated reactors consisting of a microfluidic distribution manifold, a single micro-channel reactor or a microchannel array and a 25-pm microfllter. The fluid streams come into contact via a series of interleaved high aspect ratio inlet chaimels. Perpendicular to these chaimels, a 400-pm wide channel is used to deliver catalysts as a slurry to the reaction chaimel and contains two ports to allow cross-flow of the slurry. High maldistribution, pressure drop and large heat losses may occur... 

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